38 STRATIGRAPHICAL GEOLOGY. 



more interested an insight into the stratigraphical relations of the rocks, while a study 

 of these, in connection with the specimens in the cabinet, will enable a person to ob- 

 tain in a short time a knowledge of the geology of New Hampshire that would require 

 years of study in the field. The names of the rocks that are given are for the most 

 part provisional, as they have been named from their most obvious physical properties, 

 Avithout the aid of the microscope. Where the names of individuals are referred to, 

 they are those found on the county map. Since the inhabitants are constantly chang- 

 ing, the county maps will enable a person at any time, though many years hence, who 

 desires to find the exact locality of specimens, to find them at once, without a long and 

 tedious inquiry. 



An article on the drift and the economic geology of this section will be found in a 

 subsequent chapter. 



Coos Group. 



XN the western part of New Hampshire there is quite a large area 

 where the rocks consist of wrinkled, argillaceous schists, clay slates, 

 and corrugated gray micaceous sandstones. These rocks are, however, 

 more extensively developed in the north-western portion of the state. 

 Both the schists and the sandstones contain small cavities filled with 

 ochrey yellow powder, and frequently there are calcareo-argillaceous 

 bands, with harsh, arenaceous schists, and occasionally siliceous lime- 

 stone, which weathers to a dark, reddish brown. The area of this rock 

 in New Hampshire is but a very small part of its entire area, in its exten- 

 sion north-west in Vermont and north-east into Canada. This rock is 

 extensively developed in Vermont, east of the Green Mountains, espe- 

 cially in the central part of the state, but southward it becomes a narrow 

 band. Its lithological characteristics were noticed by Prof. C. B. Adams, 

 in his preliminary report of the geology of Vermont, and its geographical 

 limits were by him defined, but he made no attempt to determine its 

 stratigraphical relations. These rocks, in their extension into Canada, 

 have been studied especially by Sir W. E. Logan and Mr. James Richard- 

 son, and they seem to form a continuous series from the province line, 

 east of Lake Memphremagog, to the Bay of Chalcur. In the report of 

 progress of the geological survey of Canada for the year 1849-50, these 

 rocks were referred to the Upper Silurian. In the report of 1863 they 

 are described as a part of the Gaspe scries, the sandstone of which was 

 supposed to be chiefly Devonian. In the report of progress for 1866-69, 



